Kiyoshi Tokita

Geometric compensation for mask expansion of colour cathode-ray tubes

Abstract It has been difficult for many years for colour-cathode-ray-tube designers fully to compensate for long-term mask expansion of low-deflection-angle C-CRTs, such as, for example, 90°-deflection C-CRTs In addition, the introduction of the invar (Fe-36Ni alloy) mask has presented designers with new problems in terms of colour-purity performance and cost effectiveness. The paper describes problems of conventional thermal compensation systems from the practical-use viewpoint. The paper also reports two unique aspects of the mask-suspension design, which are revealed using a structural-analysis program, and provide the added advantages of full geometric compensation for long-term mask expansion.